Glass containers are often composed of so-called soda-lime glass, also called soda-lime-silica glass. Many such containers are colored, for example, for aesthetic or functional purposes. Colored glass containers may be produced from soda-lime glass compositions which include one or more colorants. For example, green glass can be made from a soda-lime glass composition which includes chromium oxide (Cr2O3) as a colorant, and blue glass can be made by adding cobalt oxide (CoO) to a soda-lime glass composition. U.S. patents that illustrate colored glass compositions of this type include U.S. Pat. Nos. 3,326,702, 3,330,638, 3,345,190, 3,498,806, and 4,312,953.
Some colorants in soda-lime glass compositions may not immediately impart color to the glass. Instead, color may need to be developed by a heat-treatment process known as “striking.” In this process, glass containers are formed from a glass composition which contains “latent” colorant materials. Thereafter, the glass containers are heated to a temperature slightly above normal annealing temperatures so that the latent colorant materials in the glass interact or “strike” to impart color to the glass. U.S. patents that illustrate this method of coloring glass containers include U.S. Pat. Nos. 2,672,423, 3,513,003, and 3,627,548.
A general object, in accordance with one aspect of the disclosure, is to provide a mixture of latent colorant materials that may be introduced into a range of base glass compositions to produce lightly colored or clear glass containers that, upon heat treatment and striking, develop a deep red or visually black color. Accordingly, these glass containers may be referred to as “color-strikable.” The heat treatment or striking step is optional, which imparts flexibility to the mass production of different colored glass containers.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
In accordance with an aspect of the disclosure, there is provided a mixture of latent colorant materials formulated for use with a plurality of soda-lime silica base glass compositions having redox numbers in the range of −40 to +20 to produce a plurality of color-strikable glass compositions and a plurality of color-strikable glass containers. The mixture of latent colorant materials includes cuprous oxide (Cu2O), stannous oxide (SnO), bismuth oxide (Bi2O3), and carbon (C).
In accordance with another aspect of the disclosure, there is provided a method of making a plurality of color-strikable glass containers. In this method, a mixture of latent colorant materials is introduced into a soda-lime-silica base glass compositions having a redox number in the range of −40 to +20 to produce a color-strikable glass compositions. The mixture of latent colorant materials includes cuprous oxide (Cu2O), stannous oxide (SnO), bismuth oxide (Bi2O3), and carbon (C). Thereafter, a plurality of color-strikable glass containers is formed from the color-strikable glass compositions.
In accordance with yet another aspect of the disclosure, there is provided a method of making a plurality of color-strikable glass containers. In this method, a soda-lime-silica glass compositions is prepared including: 60-75 wt. % SiO2, 7-15 wt. % Na2O, 6-12 wt. % CaO, 0.1-3.0 wt. % Al2O3, 0.0-2.0 wt. % MgO, 0.0-2.0 wt. % K2O, and 0.01-0.30 wt. % SO3, and a latent colorant material composition is mixed into the soda-lime-silica glass composition to produce a color-strikable glass composition including: 0.0875-0.35 wt. % cuprous oxide (Cu2O), 0.06-0.5 wt. % stannous oxide (SnO), 0.0125-0.05 wt. % bismuth oxide (Bi2O3), and 0.02-0.10 wt. % carbon (C). Thereafter, a plurality of color-strikable glass containers is formed from the color-strikable glass composition.
In accordance with a further aspect of the disclosure, there is provided a color-strikable glass container having a container glass composition including a base glass portion and a latent colorant portion. The base glass portion comprises: 60-75 wt. % SiO2, 7-15 wt. % Na2O, 6-12 wt. % CaO, 0.1-3.0 wt. % Al2O3, 0.0-2.0 wt. % MgO, 0.0-2.0 wt. % K2O, and 0.01-0.30 wt. % SO3, and the latent colorant portion comprises: 0.0875-0.35 wt. % cuprous oxide (Cu2O), 0.06-0.5 wt. % stannous oxide (SnO), and 0.0125-0.05 wt. % bismuth oxide (Bi2O3).